The discharge of suspended or entrained water in air exiting a cooling tower is referred to, in the cooling tower industry, as “drift.” Devices that reduce drift are known to as “drift eliminators” or “drift reduction units” (“DRUs”). Drift eliminators are a integral component of both cross-flow and counter-flow water cooling towers. A properly performing DRU removes most of the water in an exit air stream leaving a cooling tower. Specifically, DRUs should be capable of lowering the entrained water to approximately 0.005% of the total operating gallons per minute of the cooling tower.
Drift emissions requirements, which are often mandated by environmental regulations, are significant factors in cooling tower design and operation. In one design, DRUs are stacked into cooling towers to form a continuous wall of separation between the cooling media and the fan discharging the exit air. Installation of the DRU is accomplished by stacking air channel modules into the cooling tower frame supporting the units so that the individual modules are tightly connected at their adjoining edges. The ability of a DRU to form a tight seal at the interface of the adjoining edges is dependant upon the geometry and construction of the individual DRU. Further, the degree to which the adjoined edges are sealed directly impact the DRU's ability to remove entrained water in the air exiting the cooling media. Ideally, there would be no leaks in this wall, as even small amounts of air bypassing the DRUs will result in moisture discharge that is in excess of allowable limits.
One previous DRU design included a generally sinusoidal air channel design which was constructed with the edge of each air channel module being finished with a flat sheet of material. The flat sheets were provided due to the inability to nest adjacent air channel modules effectively, without creating a gap between the modules. The flat sheets formed joint interfaces between the adjoining edges of the modules or at an otherwise exposed end thereof. However, this design was deemed unsatisfactory due to the inability to seal the flat sheets interfaces between mating modules completely and effectively, i.e., as the sinusoidal channel were not uniformly formed, they created an irregular edge at the end of each module that could not be effectively sealed against an adjoining module.
One such first generation DRU design was manufactured using a dual interlocking belt forming machine that, when compressed, created generally matching thermoformed sheets. Unfortunately, the matching sheets had inconsistent depths and undesirable dimensional variances between successive curves in the individual sheets used to form the air channels. As a result of the irregular surface of the original thermoformed parts: (a) the sinusoidal ends of these thermoformed sheets could not nest tightly together to form a completely water-tight seal and; (b) the flat sheets glued to the ends of the modules (which were used to attempt to create a water-tight seal) did not form a straight, parallel interface between modules and thereby allowed water laden air to slip through the drift eliminators and exit the cooling tower stack creating drift. In other words, the irregularities prevented the finished modules from nesting or mating close enough at the flat end sheets to prevent air leakage between the modules. As a result, sales of this first generation product were eventually discontinued because it could not consistently attain the required drift reduction levels for modern cooling towers.
As a result of the discontinuation of the first generation design, the industry turned to a plurality of second generation designs. In one such second generation design, long components having a middle portion with a substantially inverted V-shaped cross sections are employed. Air channels pass though the components in the direction perpendicular to the components' length. As a result, a middle portion of the air channels has a substantially inverted V-shape. Moreover, as the channels' inlet and outlets are positioned in horizontal passages connected to the base of the inverted V, the air channel has three turns: one where the inlet passage meets a first side of the base, one at the pinnacle of the inverted V and one where the second side of the base meets the outlet passage.
This inverted V shape facilitates nesting of other like shaped components on top of one another. However, to avoid the problems in the first generation embodiment, the components have to be as long as the cooling tower chamber into which they are to be used. In other words although the components can be nested one on top of another, modules of these components can not be nested side-by-side in a cooling tower without an unacceptable gap being created between the modules.
Unrelated to the drift elimination concerns of cooling towers, a device has long been sought to be used in commercial chicken houses which can provide ventilation while serving as a light trap and which can engage other similar devices without enabling light to pass between the devices. Light traps are necessary in commercial chicken houses to facilitate simulating multiple day cycles in a single 24 hour period. By exposing the chickens to a 12 hour “day,” the chickens lay twice as many eggs per 24 hour period. To effectively convince the chickens that the “day” is 12 hours, the chickens need to be exposed to six hour light cycles, i.e., six hours of light, six hours of darkness, six hours of light, and six hours of darkness, during each 24 hour period. However, to create a six hour darkness period effectively during actual daylight hours, the walls of the chicken house must not transmit any light, while at the same time provide ventilation.
Currently, ventilation walls in chicken houses are formed from a series of components each of which, on it own, serves sufficiently well as a ventilating light trap. However, when the components are placed against each other to create the ventilation wall, gaps are created between the components. The gaps enable an unacceptable amount of light to pass between the component, thereby enabling the chickens to know that it is “day” when they should be under the impression that it is “night.”